<!DOCTYPE html>
<html lang="en-US">
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width,initial-scale=1">
    <title>对象构造函数属性方法 | 皮卡车</title>
    <meta name="description" content="皮卡车的文档, vuepress 文档">
    <meta name="generator" content="VuePress 1.3.1">
    <link rel="apple-touch-icon" href="/apple-touch-icon.png">
  <link rel="icon" href="/favicon.ico">
  <link rel="manifest" href="/manifest.json">
  <meta name="theme-color" content="#ffffff">
  <meta name="google-site-verification" content="Ld_AEWr30siza2LmmZ12csitRGsSj9gqqEAch0UXkTc">
    
    <link rel="preload" href="/assets/css/0.styles.1a6a4f51.css" as="style"><link rel="preload" href="/assets/js/app.1f0f93c9.js" as="script"><link rel="preload" href="/assets/js/2.f28f3227.js" as="script"><link rel="preload" href="/assets/js/46.644efa88.js" as="script"><link rel="preload" href="/assets/js/3.a7eaa85f.js" as="script"><link rel="prefetch" href="/assets/js/10.7b76d38f.js"><link rel="prefetch" href="/assets/js/100.0d62a3f6.js"><link rel="prefetch" href="/assets/js/101.4916ac0c.js"><link rel="prefetch" href="/assets/js/102.0ee21f66.js"><link rel="prefetch" href="/assets/js/103.872c594c.js"><link rel="prefetch" href="/assets/js/104.0bff815e.js"><link rel="prefetch" href="/assets/js/105.46330c43.js"><link rel="prefetch" href="/assets/js/106.4ad211ca.js"><link rel="prefetch" href="/assets/js/107.d9011871.js"><link rel="prefetch" href="/assets/js/108.bab8ed0e.js"><link rel="prefetch" href="/assets/js/109.b7e4a790.js"><link rel="prefetch" href="/assets/js/11.518e0dbb.js"><link rel="prefetch" href="/assets/js/110.1eb492e8.js"><link rel="prefetch" href="/assets/js/111.ee6a2e31.js"><link rel="prefetch" href="/assets/js/112.05d655c6.js"><link rel="prefetch" href="/assets/js/113.0a4cf8f0.js"><link rel="prefetch" href="/assets/js/114.ef783947.js"><link rel="prefetch" href="/assets/js/115.11bbdb9c.js"><link rel="prefetch" href="/assets/js/116.5646126d.js"><link rel="prefetch" href="/assets/js/117.854d26bf.js"><link rel="prefetch" href="/assets/js/118.1e514b13.js"><link rel="prefetch" href="/assets/js/119.aa944f45.js"><link rel="prefetch" href="/assets/js/12.511e3547.js"><link rel="prefetch" href="/assets/js/120.1c6f450c.js"><link rel="prefetch" href="/assets/js/121.44f16ee6.js"><link rel="prefetch" href="/assets/js/122.f877b8e8.js"><link rel="prefetch" href="/assets/js/123.0563fdd5.js"><link rel="prefetch" href="/assets/js/124.4cd97316.js"><link rel="prefetch" href="/assets/js/125.a502f4ee.js"><link rel="prefetch" href="/assets/js/126.c7e94093.js"><link rel="prefetch" href="/assets/js/127.bd8aed7f.js"><link rel="prefetch" href="/assets/js/128.66063cc3.js"><link rel="prefetch" href="/assets/js/129.21bb1073.js"><link rel="prefetch" href="/assets/js/13.9e5bee4e.js"><link rel="prefetch" href="/assets/js/130.c8edfccb.js"><link rel="prefetch" href="/assets/js/131.7a1f29be.js"><link rel="prefetch" href="/assets/js/132.f589fc06.js"><link rel="prefetch" href="/assets/js/133.55ac5c9a.js"><link rel="prefetch" href="/assets/js/134.eeab127b.js"><link rel="prefetch" href="/assets/js/135.5a1571dd.js"><link rel="prefetch" href="/assets/js/136.b72b4d1c.js"><link rel="prefetch" href="/assets/js/137.678e022a.js"><link rel="prefetch" href="/assets/js/138.ba4108fa.js"><link rel="prefetch" href="/assets/js/139.0b02b599.js"><link rel="prefetch" href="/assets/js/14.b9ec07e6.js"><link rel="prefetch" href="/assets/js/140.690e4e4c.js"><link rel="prefetch" href="/assets/js/141.709da4ed.js"><link rel="prefetch" href="/assets/js/142.f2de76c0.js"><link rel="prefetch" href="/assets/js/143.4dcb17f0.js"><link rel="prefetch" href="/assets/js/144.730ef429.js"><link rel="prefetch" href="/assets/js/145.d881c754.js"><link rel="prefetch" href="/assets/js/146.f3379a41.js"><link rel="prefetch" href="/assets/js/147.eeb9ca6f.js"><link rel="prefetch" href="/assets/js/148.bb6020cd.js"><link rel="prefetch" href="/assets/js/149.1d34dea6.js"><link rel="prefetch" href="/assets/js/15.d0fa1a9d.js"><link rel="prefetch" href="/assets/js/150.599238ba.js"><link rel="prefetch" href="/assets/js/151.9655268f.js"><link rel="prefetch" href="/assets/js/152.1f843fa4.js"><link rel="prefetch" href="/assets/js/153.7af45ca6.js"><link rel="prefetch" href="/assets/js/154.eff93a56.js"><link rel="prefetch" href="/assets/js/155.ff07fba4.js"><link rel="prefetch" href="/assets/js/156.1b1814b7.js"><link rel="prefetch" href="/assets/js/157.8ac4c21b.js"><link rel="prefetch" href="/assets/js/158.aa8a0124.js"><link rel="prefetch" href="/assets/js/159.d61fdb37.js"><link rel="prefetch" href="/assets/js/16.ccd2bd60.js"><link rel="prefetch" href="/assets/js/17.ddc8fde4.js"><link rel="prefetch" href="/assets/js/18.a06e60cc.js"><link rel="prefetch" href="/assets/js/19.64b3dec9.js"><link rel="prefetch" href="/assets/js/20.3615e182.js"><link rel="prefetch" href="/assets/js/21.0c654d53.js"><link rel="prefetch" href="/assets/js/22.720aac8f.js"><link rel="prefetch" href="/assets/js/23.0dc53b91.js"><link rel="prefetch" href="/assets/js/24.d4b75b0e.js"><link rel="prefetch" href="/assets/js/25.9120702e.js"><link rel="prefetch" href="/assets/js/26.b24d89e2.js"><link rel="prefetch" href="/assets/js/27.55df94ab.js"><link rel="prefetch" href="/assets/js/28.250c68a5.js"><link rel="prefetch" href="/assets/js/29.75a3c8f3.js"><link rel="prefetch" href="/assets/js/30.8cdc2fcd.js"><link rel="prefetch" href="/assets/js/31.45303d68.js"><link rel="prefetch" href="/assets/js/32.f4225739.js"><link rel="prefetch" href="/assets/js/33.15b21267.js"><link rel="prefetch" href="/assets/js/34.5baca30b.js"><link rel="prefetch" href="/assets/js/35.5d9dfab1.js"><link rel="prefetch" href="/assets/js/36.981eadca.js"><link rel="prefetch" href="/assets/js/37.cead7f6b.js"><link rel="prefetch" href="/assets/js/38.ee6bcaf1.js"><link rel="prefetch" href="/assets/js/39.e7579788.js"><link rel="prefetch" href="/assets/js/4.494c614b.js"><link rel="prefetch" href="/assets/js/40.01d2b30b.js"><link rel="prefetch" href="/assets/js/41.19cf06ce.js"><link rel="prefetch" href="/assets/js/42.15941cde.js"><link rel="prefetch" href="/assets/js/43.66adb73c.js"><link rel="prefetch" href="/assets/js/44.8d99ed62.js"><link rel="prefetch" href="/assets/js/45.12ea9159.js"><link rel="prefetch" href="/assets/js/47.531131c7.js"><link rel="prefetch" href="/assets/js/48.b214f000.js"><link rel="prefetch" href="/assets/js/49.e42d4b72.js"><link rel="prefetch" href="/assets/js/5.7e277dc8.js"><link rel="prefetch" href="/assets/js/50.de0aa85c.js"><link rel="prefetch" href="/assets/js/51.8be2974c.js"><link rel="prefetch" href="/assets/js/52.cc067888.js"><link rel="prefetch" href="/assets/js/53.4ceb2c6b.js"><link rel="prefetch" href="/assets/js/54.b2647058.js"><link rel="prefetch" href="/assets/js/55.dc3df953.js"><link rel="prefetch" href="/assets/js/56.921a6934.js"><link rel="prefetch" href="/assets/js/57.1e24b1fd.js"><link rel="prefetch" href="/assets/js/58.f4e8ebac.js"><link rel="prefetch" href="/assets/js/59.17ab117b.js"><link rel="prefetch" href="/assets/js/6.4014218f.js"><link rel="prefetch" href="/assets/js/60.352cea9b.js"><link rel="prefetch" href="/assets/js/61.77289388.js"><link rel="prefetch" href="/assets/js/62.ec0ed919.js"><link rel="prefetch" href="/assets/js/63.c75dcb25.js"><link rel="prefetch" href="/assets/js/64.59d15a75.js"><link rel="prefetch" href="/assets/js/65.7e5a14bb.js"><link rel="prefetch" href="/assets/js/66.4e770ba1.js"><link rel="prefetch" href="/assets/js/67.0742f21a.js"><link rel="prefetch" href="/assets/js/68.a6ed34fd.js"><link rel="prefetch" href="/assets/js/69.48c9a47f.js"><link rel="prefetch" href="/assets/js/7.c5ecd7d3.js"><link rel="prefetch" href="/assets/js/70.eb477192.js"><link rel="prefetch" href="/assets/js/71.1be57009.js"><link rel="prefetch" href="/assets/js/72.6859561c.js"><link rel="prefetch" href="/assets/js/73.aae65018.js"><link rel="prefetch" href="/assets/js/74.59d76d34.js"><link rel="prefetch" href="/assets/js/75.04e23427.js"><link rel="prefetch" href="/assets/js/76.74d6eb6a.js"><link rel="prefetch" href="/assets/js/77.fba76057.js"><link rel="prefetch" href="/assets/js/78.0da94b25.js"><link rel="prefetch" href="/assets/js/79.14676976.js"><link rel="prefetch" href="/assets/js/8.08c85334.js"><link rel="prefetch" href="/assets/js/80.7494721f.js"><link rel="prefetch" href="/assets/js/81.f04f6229.js"><link rel="prefetch" href="/assets/js/82.e4c6f74b.js"><link rel="prefetch" href="/assets/js/83.81ad8dbf.js"><link rel="prefetch" href="/assets/js/84.d28e4a3d.js"><link rel="prefetch" href="/assets/js/85.d99fa7fa.js"><link rel="prefetch" href="/assets/js/86.597ecadb.js"><link rel="prefetch" href="/assets/js/87.e6d21734.js"><link rel="prefetch" href="/assets/js/88.b43a52d4.js"><link rel="prefetch" href="/assets/js/89.a5ba287d.js"><link rel="prefetch" href="/assets/js/9.658cd6b3.js"><link rel="prefetch" href="/assets/js/90.c253df12.js"><link rel="prefetch" href="/assets/js/91.8946a93d.js"><link rel="prefetch" href="/assets/js/92.8b8f1ae0.js"><link rel="prefetch" href="/assets/js/93.aa73c784.js"><link rel="prefetch" href="/assets/js/94.9326bcc7.js"><link rel="prefetch" href="/assets/js/95.46b64b79.js"><link rel="prefetch" href="/assets/js/96.61a9b0b9.js"><link rel="prefetch" href="/assets/js/97.65a03aad.js"><link rel="prefetch" href="/assets/js/98.7aa56ed0.js"><link rel="prefetch" href="/assets/js/99.a652c8d5.js">
    <link rel="stylesheet" href="/assets/css/0.styles.1a6a4f51.css">
  </head>
  <body>
    <div id="app" data-server-rendered="true"><div class="theme-container"><header class="navbar"><div class="sidebar-button"><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" role="img" viewBox="0 0 448 512" class="icon"><path fill="currentColor" d="M436 124H12c-6.627 0-12-5.373-12-12V80c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12zm0 160H12c-6.627 0-12-5.373-12-12v-32c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12zm0 160H12c-6.627 0-12-5.373-12-12v-32c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12z"></path></svg></div> <a href="/" class="home-link router-link-active"><!----> <span class="site-name">皮卡车</span></a> <div class="links"><div class="search-box"><input aria-label="Search" autocomplete="off" spellcheck="false" value=""> <!----></div> <nav class="nav-links can-hide"><div class="nav-item"><a href="/" class="nav-link">
  Home
</a></div><div class="nav-item"><a href="/guide/" class="nav-link">
  Guide
</a></div><div class="nav-item"><a href="/computer/" class="nav-link">
  计算机
</a></div><div class="nav-item"><div class="dropdown-wrapper"><button type="button" aria-label="系统" class="dropdown-title"><span class="title">系统</span> <span class="arrow right"></span></button> <ul class="nav-dropdown" style="display:none;"><li class="dropdown-item"><!----> <a href="/os/linux/" class="nav-link">
  Linux
</a></li><li class="dropdown-item"><!----> <a href="/os/manjaro/" class="nav-link">
  Manjaro
</a></li><li class="dropdown-item"><!----> <a href="/os/ubuntu/" class="nav-link">
  Ubuntu
</a></li><li class="dropdown-item"><!----> <a href="/os/centos/" class="nav-link">
  CentOS
</a></li></ul></div></div><div class="nav-item"><div class="dropdown-wrapper"><button type="button" aria-label="前端" class="dropdown-title"><span class="title">前端</span> <span class="arrow right"></span></button> <ul class="nav-dropdown" style="display:none;"><li class="dropdown-item"><!----> <a href="/frontend/javascript/" class="nav-link router-link-active">
  JavaScript
</a></li><li class="dropdown-item"><!----> <a href="https://css.shanyuhai.top/" target="_blank" rel="noopener noreferrer" class="nav-link external">
  CSS
  <svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg></a></li><li class="dropdown-item"><!----> <a href="/frontend/webpack/" class="nav-link">
  Webpack
</a></li><li class="dropdown-item"><!----> <a href="/frontend/d3js/" class="nav-link">
  D3
</a></li><li class="dropdown-item"><!----> <a href="/frontend/utils/" class="nav-link">
  Utils
</a></li></ul></div></div><div class="nav-item"><div class="dropdown-wrapper"><button type="button" aria-label="后端" class="dropdown-title"><span class="title">后端</span> <span class="arrow right"></span></button> <ul class="nav-dropdown" style="display:none;"><li class="dropdown-item"><!----> <a href="/backend/nodejs/" class="nav-link">
  Nodejs
</a></li><li class="dropdown-item"><!----> <a href="/backend/koa/" class="nav-link">
  Koa
</a></li><li class="dropdown-item"><!----> <a href="/backend/mongodb/" class="nav-link">
  MongoDB
</a></li><li class="dropdown-item"><!----> <a href="/backend/nginx/" class="nav-link">
  Nginx
</a></li></ul></div></div><div class="nav-item"><div class="dropdown-wrapper"><button type="button" aria-label="开发工具" class="dropdown-title"><span class="title">开发工具</span> <span class="arrow right"></span></button> <ul class="nav-dropdown" style="display:none;"><li class="dropdown-item"><!----> <a href="/tools/git/" class="nav-link">
  Git
</a></li><li class="dropdown-item"><!----> <a href="/tools/github/" class="nav-link">
  Github
</a></li><li class="dropdown-item"><!----> <a href="/tools/vscode/" class="nav-link">
  VSCode
</a></li><li class="dropdown-item"><!----> <a href="/tools/chrome/" class="nav-link">
  Chrome Developer tools
</a></li><li class="dropdown-item"><!----> <a href="/tools/bookmark-scripts/" class="nav-link">
  Bookmark scripts
</a></li></ul></div></div><div class="nav-item"><div class="dropdown-wrapper"><button type="button" aria-label="更多" class="dropdown-title"><span class="title">更多</span> <span class="arrow right"></span></button> <ul class="nav-dropdown" style="display:none;"><li class="dropdown-item"><!----> <a href="/more/algorithm/" class="nav-link">
  算法
</a></li><li class="dropdown-item"><!----> <a href="/more/interview/" class="nav-link">
  面试题
</a></li><li class="dropdown-item"><!----> <a href="/more/hodgepodge/" class="nav-link">
  大杂烩
</a></li><li class="dropdown-item"><!----> <a href="/more/clean/" class="nav-link">
  风格指南
</a></li><li class="dropdown-item"><!----> <a href="https://v1.vuepress.vuejs.org/zh/" target="_blank" rel="noopener noreferrer" class="nav-link external">
  VuePress1.x 官网
  <svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg></a></li></ul></div></div> <!----></nav></div></header> <div class="sidebar-mask"></div> <aside class="sidebar"><nav class="nav-links"><div class="nav-item"><a href="/" class="nav-link">
  Home
</a></div><div class="nav-item"><a href="/guide/" class="nav-link">
  Guide
</a></div><div class="nav-item"><a href="/computer/" class="nav-link">
  计算机
</a></div><div class="nav-item"><div class="dropdown-wrapper"><button type="button" aria-label="系统" class="dropdown-title"><span class="title">系统</span> <span class="arrow right"></span></button> <ul class="nav-dropdown" style="display:none;"><li class="dropdown-item"><!----> <a href="/os/linux/" class="nav-link">
  Linux
</a></li><li class="dropdown-item"><!----> <a href="/os/manjaro/" class="nav-link">
  Manjaro
</a></li><li class="dropdown-item"><!----> <a href="/os/ubuntu/" class="nav-link">
  Ubuntu
</a></li><li class="dropdown-item"><!----> <a href="/os/centos/" class="nav-link">
  CentOS
</a></li></ul></div></div><div class="nav-item"><div class="dropdown-wrapper"><button type="button" aria-label="前端" class="dropdown-title"><span class="title">前端</span> <span class="arrow right"></span></button> <ul class="nav-dropdown" style="display:none;"><li class="dropdown-item"><!----> <a href="/frontend/javascript/" class="nav-link router-link-active">
  JavaScript
</a></li><li class="dropdown-item"><!----> <a href="https://css.shanyuhai.top/" target="_blank" rel="noopener noreferrer" class="nav-link external">
  CSS
  <svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg></a></li><li class="dropdown-item"><!----> <a href="/frontend/webpack/" class="nav-link">
  Webpack
</a></li><li class="dropdown-item"><!----> <a href="/frontend/d3js/" class="nav-link">
  D3
</a></li><li class="dropdown-item"><!----> <a href="/frontend/utils/" class="nav-link">
  Utils
</a></li></ul></div></div><div class="nav-item"><div class="dropdown-wrapper"><button type="button" aria-label="后端" class="dropdown-title"><span class="title">后端</span> <span class="arrow right"></span></button> <ul class="nav-dropdown" style="display:none;"><li class="dropdown-item"><!----> <a href="/backend/nodejs/" class="nav-link">
  Nodejs
</a></li><li class="dropdown-item"><!----> <a href="/backend/koa/" class="nav-link">
  Koa
</a></li><li class="dropdown-item"><!----> <a href="/backend/mongodb/" class="nav-link">
  MongoDB
</a></li><li class="dropdown-item"><!----> <a href="/backend/nginx/" class="nav-link">
  Nginx
</a></li></ul></div></div><div class="nav-item"><div class="dropdown-wrapper"><button type="button" aria-label="开发工具" class="dropdown-title"><span class="title">开发工具</span> <span class="arrow right"></span></button> <ul class="nav-dropdown" style="display:none;"><li class="dropdown-item"><!----> <a href="/tools/git/" class="nav-link">
  Git
</a></li><li class="dropdown-item"><!----> <a href="/tools/github/" class="nav-link">
  Github
</a></li><li class="dropdown-item"><!----> <a href="/tools/vscode/" class="nav-link">
  VSCode
</a></li><li class="dropdown-item"><!----> <a href="/tools/chrome/" class="nav-link">
  Chrome Developer tools
</a></li><li class="dropdown-item"><!----> <a href="/tools/bookmark-scripts/" class="nav-link">
  Bookmark scripts
</a></li></ul></div></div><div class="nav-item"><div class="dropdown-wrapper"><button type="button" aria-label="更多" class="dropdown-title"><span class="title">更多</span> <span class="arrow right"></span></button> <ul class="nav-dropdown" style="display:none;"><li class="dropdown-item"><!----> <a href="/more/algorithm/" class="nav-link">
  算法
</a></li><li class="dropdown-item"><!----> <a href="/more/interview/" class="nav-link">
  面试题
</a></li><li class="dropdown-item"><!----> <a href="/more/hodgepodge/" class="nav-link">
  大杂烩
</a></li><li class="dropdown-item"><!----> <a href="/more/clean/" class="nav-link">
  风格指南
</a></li><li class="dropdown-item"><!----> <a href="https://v1.vuepress.vuejs.org/zh/" target="_blank" rel="noopener noreferrer" class="nav-link external">
  VuePress1.x 官网
  <svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg></a></li></ul></div></div> <!----></nav>  <ul class="sidebar-links"><li><section class="sidebar-group depth-0"><p class="sidebar-heading"><span>JAVASCRIPT</span> <!----></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/frontend/javascript/" class="sidebar-link">首页</a></li><li><a href="/frontend/javascript/arrow-function.html" class="sidebar-link">箭头函数</a></li><li><a href="/frontend/javascript/can-not-read-property-of-undefined-or-null.html" class="sidebar-link">无法访问 undefined、null 的属性</a></li><li><a href="/frontend/javascript/error.html" class="sidebar-link">Error 类型</a></li><li><a href="/frontend/javascript/function-methods.html" class="sidebar-link">对象的构造函数方法</a></li><li><a href="/frontend/javascript/implicit-coercion.html" class="sidebar-link">隐式转换</a></li><li><a href="/frontend/javascript/invocation-expression.html" class="sidebar-link">调用表达式</a></li><li><a href="/frontend/javascript/invoking-functions.html" class="sidebar-link">函数调用</a></li><li><a href="/frontend/javascript/prototype-chain.html" class="sidebar-link">原型链</a></li><li><a href="/frontend/javascript/resolve-function-call-in-jsx.html" class="sidebar-link">处理 JSX 中函数调用</a></li><li><a href="/frontend/javascript/scope-and-closures.html" class="sidebar-link">作用域与闭包</a></li><li><a href="/frontend/javascript/statements-and-expressions.html" class="sidebar-link">语句和表达式</a></li><li><a href="/frontend/javascript/this-identifier.html" class="sidebar-link">this 关键字</a></li></ul></section></li><li><section class="sidebar-group depth-0"><p class="sidebar-heading open"><span>对象方法</span> <!----></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/frontend/javascript/object-constructor-methods.html" class="sidebar-link">对象的构造函数方法</a></li><li><a href="/frontend/javascript/object-constructor-methods-freeze.html" class="sidebar-link">对象构造函数冻结方法</a></li><li><a href="/frontend/javascript/object-constructor-methods-property.html" class="active sidebar-link">对象构造函数属性方法</a><ul class="sidebar-sub-headers"><li class="sidebar-sub-header"><a href="/frontend/javascript/object-constructor-methods-property.html#object-defineproperty" class="sidebar-link">Object.defineProperty</a></li><li class="sidebar-sub-header"><a href="/frontend/javascript/object-constructor-methods-property.html#object-defineproperties" class="sidebar-link">Object.defineProperties</a></li><li class="sidebar-sub-header"><a href="/frontend/javascript/object-constructor-methods-property.html#object-getownpropertydescriptor" class="sidebar-link">Object.getOwnPropertyDescriptor</a></li><li class="sidebar-sub-header"><a href="/frontend/javascript/object-constructor-methods-property.html#object-getownpropertydescriptors" class="sidebar-link">Object.getOwnPropertyDescriptors</a></li><li class="sidebar-sub-header"><a href="/frontend/javascript/object-constructor-methods-property.html#object-getownpropertynames" class="sidebar-link">Object.getOwnPropertyNames</a></li><li class="sidebar-sub-header"><a href="/frontend/javascript/object-constructor-methods-property.html#object-getownpropertysymbols" class="sidebar-link">Object.getOwnPropertySymbols</a></li></ul></li><li><a href="/frontend/javascript/object-instance-methods.html" class="sidebar-link">对象的实例函数方法</a></li></ul></section></li><li><section class="sidebar-group depth-0"><p class="sidebar-heading"><span>数组方法</span> <!----></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/frontend/javascript/array.html" class="sidebar-link">数组</a></li><li><a href="/frontend/javascript/array-accessor-methods.html" class="sidebar-link">数组的访问方法</a></li><li><a href="/frontend/javascript/array-iteration-methods.html" class="sidebar-link">数组的迭代方法</a></li><li><a href="/frontend/javascript/array-mutator-methods.html" class="sidebar-link">数组的修改方法</a></li></ul></section></li><li><section class="sidebar-group depth-0"><p class="sidebar-heading"><span>字符串方法</span> <!----></p> <ul class="sidebar-links sidebar-group-items"><li><a href="/frontend/javascript/string-concat.html" class="sidebar-link">字符串拼接方法</a></li><li><a href="/frontend/javascript/string-format.html" class="sidebar-link">字符串格式化方法</a></li><li><a href="/frontend/javascript/string-query.html" class="sidebar-link">字符串查询方法</a></li><li><a href="/frontend/javascript/string-regexp.html" class="sidebar-link">字符串正则方法</a></li><li><a href="/frontend/javascript/string-substring.html" class="sidebar-link">字符串截取方法</a></li></ul></section></li></ul> </aside> <main class="page"> <div class="theme-default-content content__default"><h2 id="object-defineproperty"><a href="#object-defineproperty" class="header-anchor">#</a> Object.defineProperty</h2> <h3 id="_1-语法"><a href="#_1-语法" class="header-anchor">#</a> 1. 语法</h3> <div class="custom-block danger"><p class="custom-block-title">WARNING</p> <p>Object.defineProperty(obj, prop, descriptor)</p></div> <p>参数：</p> <ul><li>obj：要在其上定义属性的对象；</li> <li>prop：要定义或修改的属性的名称；</li> <li>descriptor：将被定义或修改的属性描述符。</li></ul> <p>返回值：</p> <p>传递给函数的对象。</p> <h3 id="_2-描述"><a href="#_2-描述" class="header-anchor">#</a> 2. 描述</h3> <p>defineProperty 方法会直接再一个对象上定义一个新的属性，或者修改一个对象的现有属性，并返回这个对象。</p> <p>属性描述符主要有两种形式，数据描述符、存取描述符：</p> <table><thead><tr><th>属性描述符</th> <th>描述</th> <th></th></tr></thead> <tbody><tr><td>configurable</td> <td>当且仅当该属性值为 true 时，该属性描述符才能被改变，同时该属性也能从对应的对象上被删除。</td> <td>false</td></tr> <tr><td>enumerable</td> <td>当且仅当该属性值为 true 时，该属性才能出现再对象的枚举属性中。</td> <td>false</td></tr> <tr><td>value</td> <td>该属性对应的值。</td> <td>undefined</td></tr> <tr><td>writable</td> <td>当且仅当该属性值为 true 时，value 才可以被赋值运算符改变。</td> <td>false</td></tr> <tr><td>get</td> <td>给属性提供的 getter 方法，如果没有 getter 则为 undefined。当访问该属性时，该方法会被执行。</td> <td>undefined</td></tr> <tr><td>set</td> <td>给属性提供的 setter 方法，如果没有 setter 则为 undefined。当属性值修改时，触发执行该方法。</td> <td>undefined</td></tr></tbody></table> <blockquote><p>个人在日常开发中常用场景：</p> <ul><li>尚未使用过。</li></ul></blockquote> <h3 id="_3-示例"><a href="#_3-示例" class="header-anchor">#</a> 3. 示例</h3> <ul><li><p>creating a property</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">let</span> o <span class="token operator">=</span> <span class="token punctuation">{</span><span class="token punctuation">}</span><span class="token punctuation">;</span>

Object<span class="token punctuation">.</span><span class="token function">defineProperty</span><span class="token punctuation">(</span>o<span class="token punctuation">,</span> <span class="token string">'a'</span><span class="token punctuation">,</span> <span class="token punctuation">{</span>
  value<span class="token operator">:</span> <span class="token number">37</span><span class="token punctuation">,</span>
  writable<span class="token operator">:</span> <span class="token boolean">true</span><span class="token punctuation">,</span>
  enumerable<span class="token operator">:</span> <span class="token boolean">true</span><span class="token punctuation">,</span>
  configurable<span class="token operator">:</span> <span class="token boolean">true</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>

<span class="token keyword">const</span> bValue <span class="token operator">=</span> <span class="token number">38</span><span class="token punctuation">;</span>
Object<span class="token punctuation">.</span><span class="token function">defineProperty</span><span class="token punctuation">(</span>o<span class="token punctuation">,</span> <span class="token string">'b'</span><span class="token punctuation">,</span> <span class="token punctuation">{</span>
  <span class="token keyword">get</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token keyword">return</span> bValue<span class="token punctuation">;</span> <span class="token punctuation">}</span><span class="token punctuation">,</span>
  <span class="token keyword">set</span><span class="token punctuation">(</span>newValue<span class="token punctuation">)</span> <span class="token punctuation">{</span> bValue <span class="token operator">=</span> newValue<span class="token punctuation">;</span> <span class="token punctuation">}</span><span class="token punctuation">,</span>
  enumerable<span class="token operator">:</span> <span class="token boolean">true</span><span class="token punctuation">,</span>
  configurable<span class="token operator">:</span> <span class="token boolean">true</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
o<span class="token punctuation">.</span>b<span class="token punctuation">;</span> <span class="token comment">// 38</span>
</code></pre></div></li> <li><p>adding properties and default values</p> <div class="language-js extra-class"><pre class="language-js"><code>Object<span class="token punctuation">.</span><span class="token function">defineProperty</span><span class="token punctuation">(</span>o<span class="token punctuation">,</span> <span class="token string">'a'</span><span class="token punctuation">,</span> <span class="token punctuation">{</span> value<span class="token operator">:</span> <span class="token number">1</span> <span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">// 等价于</span>
Object<span class="token punctuation">.</span><span class="token function">defineProperty</span><span class="token punctuation">(</span>o<span class="token punctuation">,</span> <span class="token string">'a'</span><span class="token punctuation">,</span> <span class="token punctuation">{</span>
  value<span class="token operator">:</span> <span class="token number">1</span><span class="token punctuation">,</span>
  writable<span class="token operator">:</span> <span class="token boolean">false</span><span class="token punctuation">,</span>
  configurable<span class="token operator">:</span> <span class="token boolean">false</span><span class="token punctuation">,</span>
  enumerable<span class="token operator">:</span> <span class="token boolean">false</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre></div></li> <li><p>custom setters and getters</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">function</span> <span class="token function">Archiver</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
	<span class="token keyword">const</span> temperature <span class="token operator">=</span> <span class="token keyword">null</span><span class="token punctuation">;</span>
  <span class="token keyword">let</span> archive <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
  
  Object<span class="token punctuation">.</span><span class="token function">defineProperty</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">,</span> <span class="token string">'temperature'</span><span class="token punctuation">,</span> <span class="token punctuation">{</span>
    <span class="token keyword">get</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
      console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'get'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
      <span class="token keyword">return</span> temperature<span class="token punctuation">;</span>
    <span class="token punctuation">}</span><span class="token punctuation">,</span>
    <span class="token keyword">set</span><span class="token punctuation">(</span>value<span class="token punctuation">)</span> <span class="token punctuation">{</span>
      temperature <span class="token operator">=</span> value<span class="token punctuation">;</span>
      archive<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span><span class="token punctuation">{</span> val<span class="token operator">:</span> temperature <span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>
  <span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
  
  <span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function-variable function">getArchive</span> <span class="token operator">=</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token keyword">return</span> archive<span class="token punctuation">;</span> <span class="token punctuation">}</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>

<span class="token keyword">let</span> arc <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Archiver</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
arc<span class="token punctuation">.</span>temperature<span class="token punctuation">;</span> <span class="token comment">// 'get!'</span>
arc<span class="token punctuation">.</span>temperature <span class="token operator">=</span> <span class="token number">11</span><span class="token punctuation">;</span>
arc<span class="token punctuation">.</span>temperature <span class="token operator">=</span> <span class="token number">13</span><span class="token punctuation">;</span>
arc<span class="token punctuation">.</span><span class="token function">getArchive</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// [{ val: 11 }, { val: 13 }]</span>
</code></pre></div></li> <li><p>inheritance of properties</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">function</span> <span class="token function">myClass</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span><span class="token punctuation">}</span>
<span class="token keyword">let</span> value<span class="token punctuation">;</span>

Object<span class="token punctuation">.</span><span class="token function">defineProperty</span><span class="token punctuation">(</span>myClass<span class="token punctuation">.</span>prototype<span class="token punctuation">,</span> <span class="token string">'x'</span><span class="token punctuation">,</span>  <span class="token punctuation">{</span>
  <span class="token keyword">get</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">return</span> value<span class="token punctuation">;</span>
  <span class="token punctuation">}</span><span class="token punctuation">,</span>
  <span class="token keyword">set</span><span class="token punctuation">(</span>x<span class="token punctuation">)</span> <span class="token punctuation">{</span>
    value <span class="token operator">=</span> x<span class="token punctuation">;</span>
  <span class="token punctuation">}</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>

<span class="token keyword">let</span> a <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">myclass</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">let</span> b <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">myclass</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
a<span class="token punctuation">.</span>x <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">;</span>
b<span class="token punctuation">.</span>x<span class="token punctuation">;</span> <span class="token comment">// 1</span>
</code></pre></div></li></ul> <h2 id="object-defineproperties"><a href="#object-defineproperties" class="header-anchor">#</a> Object.defineProperties</h2> <h3 id="_1-语法-2"><a href="#_1-语法-2" class="header-anchor">#</a> 1. 语法</h3> <div class="custom-block danger"><p class="custom-block-title">WARNING</p> <p>Object.defineProperties(obj, props)</p></div> <p>参数：</p> <ul><li>obj：在其上定义或修改属性的对象；</li> <li>props：要定义或修改的属性的名称。
<ul><li>configurable：可配置；</li> <li>enumerable：可枚举；</li> <li>value：与属性关联的值；</li> <li>wriable：可修改；</li> <li>get：该属性的 getter 函数；</li> <li>set：该属性的 setter 函数。</li></ul></li></ul> <p>返回值：</p> <p>传递给函数的对象。</p> <h3 id="_2-描述-2"><a href="#_2-描述-2" class="header-anchor">#</a> 2. 描述</h3> <p>Object.defineProperty 的复数形式。</p> <h2 id="object-getownpropertydescriptor"><a href="#object-getownpropertydescriptor" class="header-anchor">#</a> Object.getOwnPropertyDescriptor</h2> <h3 id="_1-语法-3"><a href="#_1-语法-3" class="header-anchor">#</a> 1. 语法</h3> <div class="custom-block danger"><p class="custom-block-title">WARNING</p> <p>Object.getOwnPropertyDescriptor(obj, prop)</p></div> <p>参数：</p> <ul><li>obj：需要查找的目标对象；</li> <li>prop：目标对象内属性名称。</li></ul> <p>返回值：</p> <p>如果指定的属性存在于对象上，则返回其属性描述符对象（property descriptor），否则返回 undefined。</p> <h3 id="_2-描述-3"><a href="#_2-描述-3" class="header-anchor">#</a> 2. 描述</h3> <p>描述即返回值。</p> <p>需要注意在 ES2015，第一个的参数不是对象的话就会被强制转换为对象。</p> <blockquote><p>个人在日常开发中常用场景：</p> <ul><li>尚未使用过。</li></ul></blockquote> <h3 id="_3-示例-2"><a href="#_3-示例-2" class="header-anchor">#</a> 3. 示例</h3> <ul><li><p>normal</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">const</span> o <span class="token operator">=</span> <span class="token punctuation">{</span> <span class="token keyword">get</span> <span class="token function">foo</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token keyword">return</span> <span class="token number">17</span><span class="token punctuation">;</span> <span class="token punctuation">}</span> <span class="token punctuation">}</span><span class="token punctuation">;</span>
Object<span class="token punctuation">.</span><span class="token function">getOwnPropertyDescriptor</span><span class="token punctuation">(</span>o<span class="token punctuation">,</span> <span class="token string">&quot;foo&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">// {</span>
<span class="token comment">//   configurable: true,</span>
<span class="token comment">//   enumerable: true,</span>
<span class="token comment">//   get: f foo(),</span>
<span class="token comment">//   set: undefined</span>
<span class="token comment">// }</span>

<span class="token keyword">const</span> o <span class="token operator">=</span> <span class="token punctuation">{</span>bar<span class="token operator">:</span> <span class="token number">42</span><span class="token punctuation">}</span><span class="token punctuation">;</span>
Object<span class="token punctuation">.</span><span class="token function">getOwnPropertyDescriptor</span><span class="token punctuation">(</span>o<span class="token punctuation">,</span> <span class="token string">&quot;bar&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">// {</span>
<span class="token comment">//   configurable: true,</span>
<span class="token comment">//   enumerable: true,</span>
<span class="token comment">//   value: 42,</span>
<span class="token comment">//   writable: true</span>
<span class="token comment">// }</span>
</code></pre></div></li></ul> <h2 id="object-getownpropertydescriptors"><a href="#object-getownpropertydescriptors" class="header-anchor">#</a> Object.getOwnPropertyDescriptors</h2> <h3 id="_1-语法-4"><a href="#_1-语法-4" class="header-anchor">#</a> 1. 语法</h3> <div class="custom-block danger"><p class="custom-block-title">WARNING</p> <p>Object.getOwnPropertyDescriptors(obj)</p></div> <p>参数：</p> <ul><li>obj：任意对象。</li></ul> <p>返回值：</p> <p>所指定对象的所有自身属性的描述符，如果没有任何自身属性，则返回空对象。</p> <h3 id="_2-描述-4"><a href="#_2-描述-4" class="header-anchor">#</a> 2. 描述</h3> <p>描述即返回值。</p> <blockquote><p>个人在日常开发中常用场景：</p> <ul><li>尚未使用过。</li></ul></blockquote> <h3 id="_3-示例-3"><a href="#_3-示例-3" class="header-anchor">#</a> 3. 示例</h3> <ul><li><p>normal</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">const</span> obj <span class="token operator">=</span> <span class="token punctuation">{</span>
    foo<span class="token operator">:</span> <span class="token number">1</span><span class="token punctuation">,</span>
		<span class="token keyword">get</span> <span class="token function">baz</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token keyword">return</span> <span class="token number">17</span><span class="token punctuation">;</span> <span class="token punctuation">}</span>
<span class="token punctuation">}</span><span class="token punctuation">;</span>
Object<span class="token punctuation">.</span><span class="token function">getOwnPropertyDescriptors</span><span class="token punctuation">(</span>obj<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">// {</span>
<span class="token comment">//   foo: {</span>
<span class="token comment">//     configurable: true,</span>
<span class="token comment">//     enumerable: true,</span>
<span class="token comment">//     value: 1,</span>
<span class="token comment">//     writable: true</span>
<span class="token comment">//   },</span>
<span class="token comment">// 	 baz: {</span>
<span class="token comment">//     configurable: true,</span>
<span class="token comment">//     enumerable: true,</span>
<span class="token comment">//     get: f foo(),</span>
<span class="token comment">//     set: undefined</span>
<span class="token comment">//    }</span>
<span class="token comment">// }</span>
</code></pre></div></li> <li><p>creating a shallow clone</p> <div class="language-js extra-class"><pre class="language-js"><code>Object<span class="token punctuation">.</span><span class="token function">create</span><span class="token punctuation">(</span>
  Object<span class="token punctuation">.</span><span class="token function">getPrototypeOf</span><span class="token punctuation">(</span>obj<span class="token punctuation">)</span><span class="token punctuation">,</span> 
  Object<span class="token punctuation">.</span><span class="token function">getOwnPropertyDescriptors</span><span class="token punctuation">(</span>obj<span class="token punctuation">)</span> 
<span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre></div></li> <li><p>creating a subclass</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">function</span> <span class="token function">superclass</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span><span class="token punctuation">}</span>
superclass<span class="token punctuation">.</span>prototype <span class="token operator">=</span> <span class="token punctuation">{</span>
  <span class="token comment">// Define your methods and properties here</span>
<span class="token punctuation">}</span><span class="token punctuation">;</span>
<span class="token keyword">function</span> <span class="token function">subclass</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span><span class="token punctuation">}</span>
subclass<span class="token punctuation">.</span>prototype <span class="token operator">=</span> Object<span class="token punctuation">.</span><span class="token function">create</span><span class="token punctuation">(</span>
  superclass<span class="token punctuation">.</span>prototype<span class="token punctuation">,</span>
  <span class="token punctuation">{</span>
    <span class="token comment">// Define your methods and properties here</span>
  <span class="token punctuation">}</span>
<span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre></div></li></ul> <h2 id="object-getownpropertynames"><a href="#object-getownpropertynames" class="header-anchor">#</a> Object.getOwnPropertyNames</h2> <h3 id="_1-语法-5"><a href="#_1-语法-5" class="header-anchor">#</a> 1. 语法</h3> <div class="custom-block danger"><p class="custom-block-title">WARNING</p> <p>Object.getOwnPropertyNames(obj)</p></div> <p>参数：</p> <ul><li>obj：任意对象。</li></ul> <p>返回值：</p> <p>返回给定对象可枚举和不可枚举的属性名称。</p> <h3 id="_2-描述-5"><a href="#_2-描述-5" class="header-anchor">#</a> 2. 描述</h3> <p>描述即返回值。</p> <p><code>Object.keys</code> 方法仅可获取不可枚举属性。</p> <blockquote><p>个人在日常开发中常用场景：</p> <ul><li>尚未使用过。</li></ul></blockquote> <h3 id="_3-示例-4"><a href="#_3-示例-4" class="header-anchor">#</a> 3. 示例</h3> <ul><li><p>normal</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">const</span> arr <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token string">&quot;a&quot;</span><span class="token punctuation">,</span> <span class="token string">&quot;b&quot;</span><span class="token punctuation">,</span> <span class="token string">&quot;c&quot;</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
Object<span class="token punctuation">.</span><span class="token function">getOwnPropertyNames</span><span class="token punctuation">(</span>arr<span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">sort</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// [&quot;0&quot;, &quot;1&quot;, &quot;2&quot;, &quot;length&quot;]</span>

<span class="token keyword">const</span> obj <span class="token operator">=</span> <span class="token punctuation">{</span> <span class="token number">0</span><span class="token operator">:</span> <span class="token string">&quot;a&quot;</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token operator">:</span> <span class="token string">&quot;b&quot;</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token operator">:</span> <span class="token string">&quot;c&quot;</span><span class="token punctuation">}</span><span class="token punctuation">;</span>
Object<span class="token punctuation">.</span><span class="token function">getOwnPropertyNames</span><span class="token punctuation">(</span>obj<span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">sort</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">//  [&quot;0&quot;, &quot;1&quot;, &quot;2&quot;]</span>
</code></pre></div></li></ul> <h2 id="object-getownpropertysymbols"><a href="#object-getownpropertysymbols" class="header-anchor">#</a> Object.getOwnPropertySymbols</h2> <h3 id="_1-语法-6"><a href="#_1-语法-6" class="header-anchor">#</a> 1. 语法</h3> <div class="custom-block danger"><p class="custom-block-title">WARNING</p> <p>Object.getOwnPropertySymbols(obj)</p></div> <p>参数：</p> <ul><li>obj：任意对象。</li></ul> <p>返回值：</p> <p>返回给定对象的所有 Symbol 属性的数组。</p> <h3 id="_2-描述-6"><a href="#_2-描述-6" class="header-anchor">#</a> 2. 描述</h3> <p>描述即返回值。</p> <blockquote><p>个人在日常开发中常用场景：</p> <ul><li>尚未使用过。</li></ul></blockquote> <h3 id="_3-示例-5"><a href="#_3-示例-5" class="header-anchor">#</a> 3. 示例</h3> <ul><li><p>normal</p> <div class="language-js extra-class"><pre class="language-js"><code><span class="token keyword">let</span> obj <span class="token operator">=</span> <span class="token punctuation">{</span><span class="token punctuation">}</span><span class="token punctuation">;</span>
<span class="token keyword">const</span> a <span class="token operator">=</span> <span class="token function">Symbol</span><span class="token punctuation">(</span><span class="token string">&quot;a&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">const</span> b <span class="token operator">=</span> Symbol<span class="token punctuation">.</span><span class="token function">for</span><span class="token punctuation">(</span><span class="token string">&quot;b&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>

obj<span class="token punctuation">[</span>a<span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token string">&quot;localSymbol&quot;</span><span class="token punctuation">;</span>
obj<span class="token punctuation">[</span>b<span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token string">&quot;globalSymbol&quot;</span><span class="token punctuation">;</span>

Object<span class="token punctuation">.</span><span class="token function">getOwnPropertySymbols</span><span class="token punctuation">(</span>obj<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// [Symbol(a), Symbol(b)]</span>
</code></pre></div></li></ul></div> <footer class="page-edit"><!----> <div class="last-updated"><span class="prefix">上次更新:</span> <span class="time">2020年3月17日星期二下午2点47分</span></div></footer> <div class="page-nav"><p class="inner"><span class="prev">
      ←
      <a href="/frontend/javascript/object-constructor-methods-freeze.html" class="prev">
        对象构造函数冻结方法
      </a></span> <span class="next"><a href="/frontend/javascript/object-instance-methods.html">
        对象的实例函数方法
      </a>
      →
    </span></p></div> </main></div><div class="global-ui"><!----><!----></div></div>
    <script src="/assets/js/app.1f0f93c9.js" defer></script><script src="/assets/js/2.f28f3227.js" defer></script><script src="/assets/js/46.644efa88.js" defer></script><script src="/assets/js/3.a7eaa85f.js" defer></script>
  </body>
</html>
